NINE YEARS before she enrolled her daughter at the Vineland Training School, Pearl Buck woke up out of an ether sleep and saw a bloom of plum blossoms on the table by her bed. She turned her head to see a nurse holding her newborn baby in a pink blanket. Pearl looked into the girl’s eyes.
“Doesn’t she look very wise for her age?” she asked the nurse.
It was a warm day in March 1920. Pearl Buck was twenty-eight, an American-born teacher living in northern China. She had grown up in China, her missionary parents having brought her there as a baby. After four years of college in the United States, she returned to care for her ailing mother. Soon afterward, she met an expat agricultural expert named John Lossing Buck, whom she married in 1917. For the first three years of their marriage, they lived in a remote town called Nanhsuchou. From the windows of the house, she could see miles of flat farmland. Over the green wheat, mirages of lakes and mountains flirted with her eyes. She and Lossing named their girl Caroline.
Carol, as she quickly came to be known, was a fair-haired, blue-eyed baby. A few things caught Pearl’s attention, but she didn’t give them much mind. Carol had eczema that made her scratch. Her skin gave off a peculiar musty smell. Pearl had more important things to worry about. A few weeks after Carol’s birth, Pearl’s doctor told her that she had a tumor in her uterus. She took the long journey back to the United States to have it surgically removed. The tumor proved to be benign, but her American doctors informed Pearl she would be unable to have any more children.
The Bucks moved from Nanhsuchou to the city of Nanking, where Lossing got a job teaching agriculture at the university. Pearl taught English, while Carol played in the gardens and bamboo groves surrounding their house. As Carol grew, Pearl began to worry. The babies of her friends were beginning to walk. Carol still crawled. They began to speak. Carol babbled. Her eczema grew so bad that Pearl would sometimes put bandages on her hands so that she wouldn’t rake her skin.
Pearl kept her worries to herself, partly out of shame, and partly out of her knowledge that her family would have little sympathy. Pearl’s father was a rigid fundamentalist who cared only about tallying up the souls he saved. Her mother, suffering from a lethal digestive disorder called sprue, had abandoned Christianity as she waited to die. And Lossing, Pearl discovered after they got married, was a hollow man. “He has never seen or understood anything,” she would later say.
Carol eventually learned to walk, but she still wasn’t learning to talk. She was big for her age, restless, and demanding, making her desires known with jabbering and grunts. She sniffed at visitors and jumped up on them as a friendly dog would. The things that made other children laugh or cry drew only a blank stare from Carol. Pearl’s friends assured her that everything was fine, that children begin speaking at different ages. Years later, they would confess to Pearl that they shrank from speaking the truth. They knew something was wrong.
That summer, Pearl took Carol to the seashore to play on the beach and ride donkeys through the nearby valleys. She even managed to teach Carol to speak a few words. One day that summer, Pearl went to a lecture by a local pediatrician about the health of young children. The pediatrician described some warning signs of psychological disorders, such as incessantly running around, and it sounded to Pearl as if she was talking about Carol. The next day, the pediatrician paid Pearl a visit with some other doctors. Examining Carol, they could tell that something was indeed wrong, but they couldn’t say what. For a firm diagnosis, Pearl would need to take Carol to the United States.
The Bucks already had a trip back home in the works so that Lossing could pursue a master’s degree at Cornell. He and Pearl settled into a cramped two-room apartment in Ithaca, New York, and from time to time Pearl would take Carol around the country to see doctors—psychologists, pediatricians, gland specialists. They all told her something was wrong, but none could give her a diagnosis. Yet she always left the exams with an unfocused hope that Carol would get better.
Pearl’s last trip took her to the Mayo Clinic in Minnesota. There, a young doctor gently broke the news to her: Carol had stopped developing mentally.
“Is it hopeless?” Pearl asked him.
“I think I would not give up trying,” the doctor said.
Pearl and Carol walked out of the doctor’s office and made their way down an empty hall. A small, bespectacled doctor with a clipped black mustache emerged from a room, and he asked in a crisp German accent if the other doctor had said Carol could be cured.
Pearl said he didn’t rule it out.
“She will never be well—do you hear me?” the second doctor said. “Find a place where she can be happy and leave her there and live your own life.”
Pearl staggered out of the clinic. Carol, happy to be done with the strangers, danced ahead. When she noticed that her mother had started to cry, Carol laughed.
For the rest of her time in the United States, Pearl struggled to make the best of her life. She earned a master’s degree of her own in English and wrote a few articles about China. To most Americans in the 1920s, the country was an alien giant, and so editors were happy to publish stories from someone with such deep knowledge of the place. Pearl discovered that she enjoyed writing and that she was good at it. Before returning to China, she and Lossing visited a New York orphanage and adopted a three-month-old girl they named Janice.
Back in China, Pearl became overwhelmed by sadness over Carol. She couldn’t even bear to listen to music. When guests came to the house, she would put on a brave face, but as soon as they left, she would let her sorrow have its way. Pearl began writing stories along with her essays, imagining the lives of Chinese people around her. Carol would become intensely jealous as Pearl became absorbed in her work. She threw porridge at her mother and used handfuls of potting soil to clog the keys of Pearl’s typewriter.
While the Bucks had been away, China had grown far more dangerous. The Kuomintang and its enemies had begun battling for control of different pieces of the country. For two years, the fighting remained far from Nanking, but in 1927 it reached the city. As foreigners were shot and raped, the Bucks hid in the hut of a Chinese woman Pearl knew. Pearl kept Carol and Janice quiet so that they wouldn’t draw the attention of nearby soldiers. She vowed to herself to kill her girls before letting the soldiers take them away.
The attacks subsided after American and British gunships arrived in Nanking and fired on the city. The Bucks took the opportunity to flee, making their way to Shanghai. Shanghai proved only a brief stopover for them; the fighting drove the Bucks out of China altogether. They ended up in Japan, surviving in a remote forest cabin for months on fish, fruit, and rice.
Once China settled down again into a relative calm, the Bucks returned. Pearl now became painfully aware of how the children of her friends were developing and thriving while Carol, now eight, still acted like a toddler. When she tried to teach Carol to write, her daughter managed to learn only a few words. During one of their lessons, Pearl took the pencil from Carol and was startled to discover that her daughter’s hand was drenched in sweat from all her effort. Pearl was ashamed that she had made Carol so miserable and decided to stop forcing her to try to become like other girls. As her mother, Pearl would only try to make Carol happy.
“I realized I must leave her in some place,” Pearl later recalled, “and my heart is wrenched in two at the thought.”
Aside from the dread of separation, Pearl also recognized that she faced some grim economics. Lossing thought Carol should go to a state institution. The idea terrified Pearl, but she knew they didn’t have the money to pay for a private school. Pearl realized she would have to find the funds on her own. “I had found out enough to know that the sort of place I wanted my child to live in would cost money that I did not have,” she later wrote.
Her income from teaching was meager, and she made even less from writing articles for American magazines. She wondered if fiction might pay better. By then she had finished her first novel, which she called East Wind: West Wind. She got an idea for a second novel that might sell well. Whenever she found a free ten minutes between chores or caring for Carol, she would sit down to her typewriter and write about the adventures of a Chinese farmer she named Wang Lung.
In 1929, the Bucks traveled back to the United States. As Lossing negotiated a new grant for his work on Chinese agriculture, Pearl searched for a place where Carol could live. Many of the visits left her chilled. At one institution, the children were clothed in burlap and herded like dogs. Eventually, Pearl ended up in southern New Jersey, at a farm where the children seemed happy.
“I saw children playing around the yards behind the cottages, making mud pies and behaving as though they were at home,” she later recalled. “I saw a certain motto repeated again and again on the walls, on the stationery, hanging above the head’s own desk. It was this: ‘Happiness first and all else follows.’”
In September 1929, Pearl Buck enrolled her daughter at the Vineland Training School. Emma Wolverton had been taken out of the school fifteen years earlier, and a decade had passed since Henry Goddard had left. The enthusiasm for eugenics had left the place as well. In the 1920s, Vineland psychologists did important research on classifying different forms of feeblemindedness—what are now known as intellectual developmental disorders. They created a test to track the social development of children that’s known today as the Vineland Social Maturity Scale.
Pearl stayed with friends for a month while Carol settled in at the school. It was the first time they had been separated in her life, and for Pearl it was torture. She listened for her daughter’s calls for help in the night, her steps on the stairs. “Only the thought of a future with the child grown old and me gone kept me from hurrying to the railway station,” she said.
Pearl went to New York to show the manuscript for East Wind: West Wind to a publisher named Richard Walsh. He bought it, along with the new novel she was in midst of writing. When she and Lossing returned to China in 1930, she worked on nothing else, losing herself in the story of Wang Lung to keep her pain at bay. When she sent the book to Walsh, he gave her a name for it: The Good Earth.
Pearl’s gritty story about a poor Chinese hero was an unfamiliar one to American readers. If they had read any fiction from China, it was classical tales about the country’s elite. The Good Earth, published in the midst of America’s Great Depression, felt like an Asian parallel to The Grapes of Wrath. In 1932, it earned Pearl the Pulitzer Prize, and it also proved a smashing commercial success. In just the first eighteen months after publication, Buck earned $100,000, and the book would earn hundreds of thousands more during her lifetime.
Pearl had only wanted to pay for a home for Carol. Instead, she became a celebrity. In quick succession, Pearl moved back to the United States, got a Nevada divorce from Lossing, married Walsh, bought a farm in Pennsylvania, and adopted more children. Hollywood turned The Good Earth into a box-office hit, while Pearl found herself in fierce demand for lectures around the country.
Pearl made savvy use of her new fame to champion political causes, especially civil rights. Growing up in China, she became keenly aware of the contempt some Chinese had for her simply because she was white. When she returned to the United States, she scoffed at the idea that the country’s blacks and whites were biologically distinct in any meaningful way, calling humanity “a creature hopelessly mongrel.” In 1938, just seven years after publishing The Good Earth in the hope of taking care of Carol, Pearl S. Buck won the Nobel Prize in Literature. When she got the news, she responded in Chinese: “Wo pu hsiang hsin.” (I don’t believe it.)
The more stories that Pearl told, the more the world clamored to hear her own. But she refused to reveal Carol’s secret. “It is not a shame at all but something private and sacred, as sorrow must be,” Pearl wrote to a friend. When reporters asked about her family, she would say she had two daughters, one of whom was away at school. An old friend from Nanking was interviewed by an Ohio newspaper and recalled Pearl’s suffering over Carol. Pearl got wind of the story and arranged to have it quashed. She wanted to protect Carol, but herself as well. “I would gladly have written nothing if I could have just an average child in Carol,” she once said.
From the profits on The Good Earth, Pearl gave the Vineland School $40,000, guaranteeing Carol a lifetime of care. Pearl later paid for the construction of a new two-story cottage where Carol could live with fifteen other girls, complete with a French provincial bedroom set, a phonograph, and a collection of records. (Carol liked hymns, hated jazz.) Once Pearl returned to the United States, she would visit Carol as often as she could—sometimes as often as once a week—and sometimes brought her back to her farm in Pennsylvania for a few days. Pearl thus got to watch Carol grow up. She began to bathe and dress herself, even to tie her shoelaces. She learned to eat with a fork and spoon, to sew, and to use words to tell others what she needed. She roller-skated. She loved to ride a tricycle around the school grounds. Decades later, people would sometimes see a gray-haired woman pedaling still.
By 1940, Pearl had reached a kind of melancholy peace with Carol’s fate. “All sense of flesh, of my flesh, is gone,” she wrote in her journal. “I feel toward her as tenderly as ever, but I am no longer torn. I am, I suppose, what may be called ‘resigned’ at last. Agony has become static—it is true but I will not disturb it or allow it to move in me.”
Pearl continued publishing at an industrial pace. But her literary reputation had grown dim. The men who came to dominate American mid-century literature treated her writing merely as women’s novels. Pearl tried to write about life in the United States, but readers thought of her only as a chronicler of China. She also made a growing number of enemies with her political activity. Even at the height of World War II, she criticized the American government, asking how the United States could fashion itself as the enemy of fascism when it accepted white superiority at home and promoted imperialism abroad. After the war, the FBI decided she was a Communist in spirit if not in party membership.
Pearl could sense that hostility was growing around her, but she didn’t stop working for her causes. She even took up new ones. Having adopted five children, she spoke out against orphanages and foster homes. Before she knew it, a desperate mother had dropped off a child at her farm. Pearl responded by creating a private adoption agency specializing in finding homes for Amerasian children who were rejected by both sides of their family. Pearl raised money for the research at Vineland, and by the 1940s she was in charge of fund-raising for the entire school.
One of the fund-raisers she worked with urged her to publish something about Carol, to help draw attention to the school. At first, Pearl found the requests intensely annoying. But eventually the fund-raiser won her over. She sat down and began to write about Carol. “I have been a long time making up my mind to write this story,” she began.
Pearl presented a clear-eyed account of Carol’s childhood and her own pain, shame, and reconciliation. She confessed to thinking how her daughter might be better off dead. She recounted how she learned to stop blaming Carol for what was not her fault, and to recognize her right to develop her mind as far as nature would allow.
“It was my child who taught me to understand so clearly all people are equal in their humanity and that all have the same human rights,” Pearl wrote. “Though the mind has gone away, though he cannot speak or communicate with anyone, the human stuff is there, and he belongs to the human family.”
Pearl published her essay in Ladies’ Home Journal in May 1950, and it was later released as a short book called The Child Who Never Grew. All the royalties went to the Vineland Training School. In 1950, when intellectual developmental disability was still a source of shame and confusion, her frankness was nothing short of astonishing, especially coming from a bestselling, Nobel Prize–winning writer. The Child Who Never Grew was translated into thirteen languages, and Pearl got mailbags full of letters from parents of children like Carol. She answered every one.
At the end of the book, Pearl called for better care for people like Carol and urged that more research go into understanding intellectual developmental disorders, pointing to the work carried out at Vineland as an example of what needed to be done. She highlighted Goddard’s intelligence testing and the Vineland Social Maturity Scale.
It’s telling that Pearl didn’t mention the research that first brought the Vineland Training School to international attention: Goddard’s study of heredity. In fact, Pearl took great pains to scrub Carol’s story clean of any possible hereditary taint. She declared that there was no trace of mental retardation in her own family or in Lossing’s. Carol’s story, in other words, had nothing to do with the other famous tale of a Vineland student, The Kallikak Family. “The old stigma of ‘something in the family’ is all too often unjust,” Pearl wrote.
Unbeknownst to Pearl, there was something in the family after all. It was not an inheritance of sin or degeneration, however. It was a hereditary disease. In fact, a doctor had come to Vineland a decade before Pearl published The Child Who Never Grew and correctly diagnosed Carol with the disorder. No one had told Pearl, and she would have to wait another decade to find out for herself.
Eight years after Pearl Buck gave birth to Carol, a woman in Oslo named Borgny Egeland had a girl of her own. Liv Egeland seemed a healthy baby at first, although Borgny was puzzled by the odor of her hair, skin, and urine. It reminded her of a horse stable. Her puzzlement turned to worry as Liv reached age three unable to utter a single word. Yet her doctor, finding nothing wrong with Liv, told Borgny to give her more time.
Unlike Pearl Buck, Borgny Egeland was able to bear another child. In 1930, she gave birth to a son, Dag, who gave off the same musty odor as Liv. And later he also failed to learn how to speak. Borgny searched for a doctor who could explain this bizarre coincidence. By the time Liv was six, she could say only a few words and had trouble walking. Dag, now four, couldn’t talk at all. He was unable to eat, drink, or walk on his own.
The doctors Borgny consulted had no explanation for why both of her children had developed the same symptoms. Nor could they offer any treatment. Borgny refused to share their resignation. She kept visiting doctors until she ran out of names, and then she paid a woman to give her children baths in herb-soaked water. She sought help from a psychic. Finally, Borgny learned that her sister was acquainted with a doctor at Oslo University Hospital who was an expert on metabolic disorders. She asked her sister to contact the doctor, named Asbjørn Følling, to see if he thought their odor and their intellectual development were linked.
Følling had never heard of such a thing. He doubted he could help, but he didn’t want to disappoint Borgny after she had suffered so much. He invited her to bring the children to see him. The exam revealed nothing new. But Følling also asked Borgny to bring him some of Liv’s urine so that he could carry out some chemical tests to track down the source of the odor.
Følling carried out his experiments in a makeshift lab in the attic of the medical ward. He added drops of ferric chloride to Liv’s urine to test for diabetes. If Liv had the disease, it would turn purple. Instead, her urine turned green. Følling had never seen such a thing. He hadn’t even heard of such a thing happening before. Baffled, Følling asked Borgny to bring him some of Dag’s urine. When Følling ran the test again, the urine shimmered green once more.
Følling searched through the medical literature for an explanation, but no one had ever observed the reaction. He wondered if Borgny was giving her children aspirin or some other medicine that was tinting the urine. As a test, he asked Borgny to keep her children off any medication for a week. When he experimented on their urine again, it still turned green.
It took two months of experiments—and twenty-two liters of Egeland urine—for Følling to finally find the cause. The children’s urine was loaded with a compound not found in healthy people—a cluster of carbon, oxygen, and hydrogen atoms known as phenylpyruvic acid.
Based on his deep knowledge of human metabolism, Følling came up with a hypothesis to explain the strange chemistry. Proteins are made of building blocks called amino acids. One amino acid is called phenylalanine, which people must get from their food. Any extra phenylalanine people don’t use to make proteins gets broken down by enzymes in the liver. Følling reasoned that the Egeland children were not breaking down their phenylalanine. Somehow, the rising level of phenylalanine harmed the children. Some of it was converted into a similar molecule, phenylpyruvic acid, and washed out of their bodies in their urine.
To test his idea, Følling examined other children with similar symptoms. He ended up finding the green signature in the urine of ten patients in total. They included three pairs of siblings—a coincidence that led Følling to suspect the condition was a hereditary disorder.
Yet Følling could plainly see that Borgny Egeland and all the other parents of these children were healthy. Some of them had other children who were healthy as well. The disorder must be caused by a recessive factor, Følling reasoned. Each parent was a carrier, with one defective copy of some unknown gene, and some of their children had the misfortune of inheriting a bad copy from both of them.
Følling found support for this hypothesis when he followed up with two parents, each of whom had gotten remarried. Between them, they had twelve more children. All of their offspring from their new marriages were healthy, and none of them had urine that turned green. The recessive factor was probably very rare in Norway, Følling reasoned, meaning that the odds of marrying two people who were carriers was next to zero. The children of the second marriages might inherit one recessive factor at most, meaning that they could not develop the disease.
Følling quickly wrote up his discovery and gave the disease a name: imbecillitas phenylpyruvica. Not since Archibald Garrod had discovered that the black urine of alkaptonuria was a hereditary disorder had someone found such a clear-cut case. Yet few scientists paid Følling’s 1934 paper much notice. He could not say precisely what was wrong in people with the disease. Nor could he account for how a problem with phenylalanine could affect the brain.
Only a small circle of scientists who studied intellectual developmental disorders recognized how important his findings were. Even if imbecillitas phenylpyruvica was rare, it still represented what Henry Goddard had been chasing after: a hereditary cause of feeblemindedness. Følling’s study was even more significant because he had invented a straightforward way to give a precise diagnosis.
One of the first doctors to take up Følling’s test was a British doctor named Lionel Penrose. Although only in his mid-thirties at the time, Penrose had already become a leading expert on intellectual developmental disability in Britain. He had climbed the ranks swifly, having come late to medicine. Penrose had started out studying mathematical logic at Cambridge, and then he traveled to Vienna to investigate the psychology of mathematical thinking. When that work hit a dead end, Penrose got curious about mental disorders and what they might reveal about the mind. At age twenty-seven, he returned to Cambridge to study medicine. Four years later, now a freshly minted MD, Penrose became a medical research officer at the Royal Eastern Counties Institution at Colchester, a home for “mental defectives.”
Penrose entered the profession as a passionate critic of eugenics, dismissing it as “pretentious and absurd.” In the early 1930s, eugenics still had a powerful hold on both doctors and the public at large—a situation Penrose blamed on lurid tales like The Kallikak Family. While those stories might be seductive, eugenicists made a mess of traits like intelligence. They were obsessed with splitting people into two categories—healthy and feebleminded—and then they would cast the feebleminded as a “class of vast and dangerous dimensions.”
Penrose saw intelligence as a far more complex trait. He likened intelligence to height: In every population, most people were close to average height, but some people were taller and shorter than average. Just being short wasn’t equivalent to having some kind of a height disease. Likewise, people developed a range of different mental aptitudes.
Height, Penrose observed, was the product of both inherited genes and upbringing. He believed the same was true for intelligence. Just as Mendelian variants could cause dwarfism, others might cause severe intellectual developmental disorders. But that was no reason to leap immediately to heredity as an explanation.
“That mental deficiency may be to some extent due to criminal parents’ dwelling ‘habitually’ in slums seems to have been overlooked,” Penrose said. He condemned the fatalism of eugenicists, as they declared “there was nothing to be done but to blame heredity and advocate methods of extinction.”
The wrongheaded ideas of eugenicists led them to wrongheaded solutions, such as sterilization. Even if a country did sterilize every feebleminded citizen, Penrose warned, the next generation would have plenty of new cases from environmental causes. “The first consideration in the prevention of mental deficiency is to consider how environmental influences which are held responsible can be modified,” Penrose declared. He suspected that many cases of mental deficiency were caused by a mother’s syphilis or X-ray tests during pregnancy.
At Colchester, Penrose launched a study he hoped would lead to more humane, more effective treatments for intellectual developmental disorders. He set out to classify the disorders and determine some of their causes. Over the course of seven years, he examined 1,280 subjects and carefully studied their families as well. Drawing on his expertise in mathematics, Penrose developed sophisticated statistical methods to search his data for links among mental deficiency, heredity, and the environment.
As soon as Penrose heard of Følling’s discovery, he wanted to try it out for himself. It was so simple, he later wrote, that it was puzzling no one had discovered it before. Penrose ordered that urine from 500 patients at Colchester be put to Følling’s test. Out of those samples, 499 did not change color. But a single sample turned green.
The emerald urine belonged to a nineteen-year-old man who had never walked or talked. He spent his days rocking back and forth, his wasted arms and legs bent close to his body. After the test, Penrose paid a visit to the man’s family. His parents were hardworking and healthy, although his father was convinced that people were poisoning him. Their other children were all relatively normal, except their five-year-old son. Like his older brother, the boy could not walk or speak. Penrose tested the urine of the children and found that they were all normal—except the five-year-old boy.
Studying these and other cases, Penrose proposed that a single hereditary factor was responsible for the disorder. While people with two copies of the recessive factor might be rare, he suggested that many more people might have a single copy. When Penrose published his research, he decided not to use the original name for the disease, imbecillitas phenylpyruvica. He preferred a new name coined by his collaborator, Juda Quastel: phenylketonuria. It was, Penrose boasted, “preferable to the original more cumbersome designation.” That name has stuck ever since, although it’s often shortened to PKU—which Penrose called “an abominable abbreviation.”
Over the next few years, an American researcher named George Jervis confirmed Penrose’s hypothesis and worked out the chemistry of the disease. Normally, an enzyme known as phenylalanine hydroxylase breaks down the body’s extra phenylalanine. In people with PKU, the enzyme doesn’t work. The body’s phenylalanine reaches toxic levels and spreads throughout the body, wreaking havoc.
As the biology of PKU became clearer, Penrose realized that it might not be inevitable, even if it was hereditary. Penrose reasoned that a diet low in phenylalanine might prevent people with PKU from becoming poisoned.
But because phenylalanine is so abundant in food, Penrose found it difficult to draw up a diet for his patients. He restricted the diet of one patient to only fruit, sugar, and olive oil, supplemented with vitamin pills. It lowered his patient’s phenylalanine levels for a couple of weeks, but they bounced back up. Seeking help, Penrose contacted Frederick Gowland Hopkins, a Cambridge biochemist who had won the Nobel Prize in 1929 for the discovery of vitamins. When Penrose told Hopkins about PKU, Hopkins declared that a diet for the disorder would cost a thousand pounds a week.
Penrose abandoned a search for a diet, but he continued to study people with PKU. Whenever he visited a new institution, he would sniff the air for a musty odor. If he discovered patients who he suspected of having PKU, he would examine them for other telltale features of the condition, such as fair hair and blue eyes. Then he would order a simple urine test.
In 1939, while on a trip through the United States, Penrose paid a visit to the Vineland Training School. There he met the nineteen-year-old Carol Buck. “I was informed that this patient was the daughter of a distinguished writer but that, in spite of obtaining all the best opinions in the United States, no cause for the defect had been found,” Penrose later wrote.
Penrose met Carol at the cottage her mother, Pearl, had built for her. “Everything was beautifully appointed,” he recalled. But when Penrose sniffed the air, he detected the familiar mustiness. He noticed Carol’s blue eyes and fair hair. He checked her reflexes. “I felt quite certain of the diagnosis and told my hosts what I thought,” Penrose said.
Penrose was dismayed that his hosts didn’t know what he was talking about. It had been five years since Følling had published the first account of PKU. Even at an advanced institution like Vineland, however, no one recognized it as a possible cause of retardation. “‘Impossible,’ they said. ‘How can you come here and in a few minutes find something which all our best clinicians have missed?’” Penrose wrote.
The next morning, Penrose tested Carol’s urine. He saw “the wonderful green color.” But no one at the school ever told Carol’s mother about Penrose’s diagnosis.
Penrose, a lifelong pacifist, sat out World War II in Canada. In 1945, he got an invitation back home, to become the next Galton Professor of Eugenics at University College London and director of the Galton Laboratory. The irony of the titles was not lost on him.
Francis Galton, the scientist who had coined the term eugenics, had left some of his family fortune to pay for a professor to run a eugenics research lab, gathering data about heredity in the hopes of improving the human race. After Galton’s death in 1911, the lab buzzed with research for three decades, until it fell to German bombs. Penrose agreed to rebuild it, but it would not be the same when he was done. He sought to wipe eugenics away. He even changed the name of his position to Galton Professor of Human Genetics—but only after a legal battle that lasted until 1963.
As the new Galton Professor, Penrose was required to give an inaugural lecture. He used the opportunity to let the world know that things had changed, and he used PKU as a case study. The title of his talk was “Phenylketonuria: A Problem in Eugenics.”
As Penrose drafted his lecture in 1945, the memories of the Holocaust were still horrifically fresh. It had been less than a year since Auschwitz, Dachau, and Bergen-Belsen had been liberated. The Nazis had justified the horrors of their “race hygiene” by pointing to the work of eugenicists. In the postwar years, Penrose now worried that eugenics might survive their defeat. Leading eugenicists in England and other countries were still pushing their agenda. In the United States, sterilization laws justified on the basis of eugenics remained on the books, and people were being regularly robbed of the chance to have children.
In his lecture, Penrose directed his wrath at lingering eugenicists, showing how their calls to manage human reproduction for the betterment of the species were absurd—“pernicious ideas based upon emotional bias,” as he put it. And Penrose used PKU as a case study for why the eugenics agenda should be thrown out.
By 1946, scientists had studied some five hundred people with PKU, and their family histories clearly demonstrated that the disease was hereditary. In other words, children had to inherit the same version of a gene from both parents. Scientists still didn’t know what genes were, but to a eugenicist, Penrose speculated, that wouldn’t matter. To get rid of PKU, all that would be required would be to stop people from passing the gene down to future generations.
“This view, however, is incorrect,” Penrose said. “We cannot take the same attitude here that we might with regard to some noxious pest and simply ask to have the offending genes exterminated.”
PKU was a recessive condition, meaning that a child had to inherit two faulty copies of the same gene to develop the diseases. As far as Penrose and other scientists could tell, people with a single copy of the defective gene were healthy—so healthy, in fact, that it was impossible to identify carriers until they had children with PKU. Based on the number of cases he had found, Penrose estimated that 1 percent of people in Great Britain were carriers. (Later research would indicate that the true figure is probably twice that.)
“To eliminate the gene from the racial stock would involve sterilizing 1% of the normal population, if carriers could be identified,” Penrose declared. “Only a lunatic would advocate such a procedure to prevent the occurrence of a handful of harmless imbeciles.”
When Penrose treated people with PKU, their relatives would anxiously ask him how likely it was that they might be carriers. Should they not have children? Penrose worked through the odds. The chances of a sibling of someone with PKU being a carrier is two in three. Penrose estimated that the chances of a prospective mate also being a carrier was one in a hundred. And the chance of a child of two carriers inheriting PKU was one in four. Multiplying all those probabilities together led Penrose to conclude that the chance of a relative of someone with PKU having a child with PKU was only one in six hundred.
“In my opinion,” Penrose said, “this risk is no adequate ground for discouraging the union.”
In a sly aside, Penrose also noted that PKU undermined the Nazi myth of an Aryan race that was superior to races of Jews or blacks. In the United States, Jervis had not found any Jews or blacks with PKU. Instead, many of the people with the disease were Germans and Dutch. “A sterilisation programme to control phenylketonuria confined to the so-called Aryans would hardly have appealed to the recently overthrown government of Germany,” Penrose said.
To finish up his lecture, Penrose predicted that the story of PKU would turn out to be similar for many other diseases. “Many rare recessive disabilities have been identified in man, and doubtless many more lie awaiting detection,” he said. “Not improbably, about two people out of every three are carriers of at least one serious recessive defect.”
Humanity, in other words, was not some genetically uniform stock that could be purged of a few defectives. Penrose saw our species as rich with genetic diversity, and forever falling short of genetic perfection. To eliminate imperfection would demand eliminating humanity itself.
After his attack on eugenics, Penrose went on to build the first large medical genetics program, designed to identify new hereditary disorders. The geneticists under Penrose’s leadership in the early 1950s examined patients, ran blood tests, and drew pedigrees. They traced the inheritance of genes, despite still not knowing what genes are. But if they had taken a stroll down Bloomsbury Street to King’s College London, they could have watched a woman take X-ray pictures that would soon start to unravel that mystery.
By the 1920s, Thomas Hunt Morgan and his colleagues had persuaded their fellow scientists that genes were physical things, located in chromosomes. Chromosomes were chemical mixtures, including proteins as well as a mysterious molecule called deoxyribonucleic acid, or DNA for short. By the early 1950s, researchers had performed some elegant experiments with bacteria and viruses that made it clear that DNA, not proteins, was the stuff of genes. When viruses infected bacteria, for example, they only injected DNA; none of their proteins made it into the cells.
In 1950, a thirty-year-old scientist named Rosalind Franklin arrived at King’s College London to study the shape of DNA. She and a graduate student named Raymond Gosling created crystals of DNA, which they bombarded with X-rays. The beams bounced off the crystals and struck photographic film, creating telltale lines, spots, and curves. Other scientists had tried to take pictures of DNA, but no one had created pictures as good as Franklin had. Looking at the pictures, she suspected that DNA was a spiral-shaped molecule—a helix. But Franklin was relentlessly methodical, refusing to indulge in flights of fancy before the hard work of collecting data was done. She kept taking pictures.
Two other scientists, Francis Crick and James Watson, did not want to wait. Up in Cambridge, they were toying with metal rods and clamps, searching for plausible arrangements of DNA. Based on hasty notes Watson had written during a talk by Franklin, he and Crick put together a new model. Franklin and her colleagues from King’s paid a visit to Cambridge to inspect it, and she bluntly told Crick and Watson they had gotten the chemistry all wrong.
Franklin went on working on her X-ray photographs and growing increasingly unhappy with King’s. The assistant lab chief, Maurice Wilkins, was under the impression that Franklin was hired to work directly for him. She would have none of it, bruising Wilkins’s ego and leaving him to grumble to Crick about “our dark lady.” Eventually a truce was struck, with Wilkins and Franklin working separately on DNA. But Wilkins was still Franklin’s boss, which meant that he got copies of her photographs. In January 1953, he showed one particularly telling image to Watson. Now Watson could immediately see in those images how DNA was shaped. He and Crick also got hold of a summary of Franklin’s unpublished research she wrote up for the Medical Research Council, which guided them further to their solution. Neither bothered to consult Franklin about using her hard-earned pictures. The Cambridge and King’s teams then negotiated a plan to publish a set of papers in Nature on April 25, 1953. Crick and Watson unveiled their model in a paper that grabbed most of the attention. Franklin and Gosling published their X-ray data in another paper, which seemed to readers to be a “me-too” effort.
Franklin died of cancer five years later, while Crick, Watson, and Wilkins went on to share the Nobel prize in 1962. In his 1968 book, The Double Helix, Watson would cruelly caricature Franklin as a belligerent, badly dressed woman who couldn’t appreciate what was in her pictures. That bitter fallout is a shame, because these scientists had together discovered something of exceptional beauty. They had found a molecular structure that could make heredity possible.
DNA, they discovered, is a pair of strands twisted into a double helix. Between the strands, a series of compounds called bases bonded to each other. Over the next thirty years, scientists worked out how this structure allowed DNA to carry genes. Each gene is a stretch of DNA, made up of thousands of bases. Each base can take one of four different forms: adenine, cytosine, guanine, and thymine—A, C, G, T for short. A cell carries out a series of chemical reactions to translate a gene’s sequence of bases into a protein. A cell first makes a copy of the gene, creating a single-stranded series of bases called ribonucleic acid, or RNA. That RNA molecule is taken up by a molecular factory called a ribosome, which reads the sequence of RNA and builds a corresponding protein.
The discovery of DNA seemed to reduce heredity to a reliably simple recipe. It came down to turning one DNA molecule into a pair. A cell’s molecular machinery pulled apart the two strands of a DNA molecule and then assembled a new strand to accompany each of them. Each base could bond only to one other: A to T, C to G. The cell could thus build two perfect copies of the original DNA—like engendering like, but on an atomic scale.
Sometimes cells make mistakes, however. These errors leave one of the new DNA molecules altered. A single base may change from A to C. A stretch of a hundred bases may be accidentally copied out twice. A thousand bases may be cut out altogether. These are the mutations that scientists like Hugo de Vries and Thomas Hunt Morgan spent years trying to figure out. Mutations can produce new versions of genes—alleles, as they came to be known. Sometimes alleles work the same as before. But, in cases such as PKU, they fail to work at all.
Later generations of scientists would use this discovery to determine the molecular details of PKU. The enzyme Jervis had discovered, phenylalanine hydroxylase, is encoded by a gene called PAH. In our livers, cells translate the PAH gene into the enzyme, which can then break down phenylalanine. In carriers, such as Pearl and Lossing Buck, one copy of the PAH gene carries a mutation that prevents cells from making the enzyme.
Pearl and Lossing had no idea that anything was wrong in their DNA, because their other copy of the PAH gene lacked the mutation. They could make enough phenylalanine hydroxylase for their metabolism to run properly. But when a child like Carol inherited a faulty copy of the PAH gene from both her parents, she could not make any working enzymes and suffered the consequences.
Fifty years would pass after Følling and Penrose proposed that PKU was caused by recessive factors before scientists finally saw the factors with their own eyes. By then, however, the lives of people with PKU had already dramatically improved. A child born with PKU, if properly cared for, would never have to face a future like that of Carol Buck.
The journey to a treatment started in 1949, when a British woman named Mary Jones brought her seventeen-month-old daughter, Sheila, to a Birmingham hospital. Sheila couldn’t stand or even sit up. Nor did she take an interest in her surroundings. A doctor at the hospital named Horst Bickel examined Sheila and informed Jones that she had PKU. “Her mother was not at all impressed when I showed her proudly my beautiful paper chromatogram with the very strong phenylalanine (Phe) spot in the urine of her daughter proving the diagnosis,” Bickel later recalled.
Jones wanted to know what Bickel was going to do now that he had discovered Sheila’s disease. There was nothing to do, Bickel explained.
Jones rejected his answer. She came back the next morning to demand help. When he turned her down, she came back every morning with the same demand.
“She was very upset and did not accept the fact that at the time no treatment was known for PKU,” Bickel said. “Couldn’t I find one?”
At the time, Bickel had little reason to think he could. Lionel Penrose had already tried to design a diet for PKU, without any results to show for it. Penrose became convinced that mental retardation wasn’t caused by the inability to convert phenylalanine. Instead, he thought, the two symptoms both arose from an unknown source. A diet was no more likely to cure PKU retardation than eyeglasses would make an old man’s wrinkles disappear.
Jones was so insistent, though, that Bickel decided to talk to some of his colleagues about a diet for PKU. He learned that a biochemist in London named Louis Wolff had tried concocting a broth that could provide protein to people with PKU without poisoning them with phenylalanine. When he proposed feeding his broth to patients, his superiors at Great Ormond Street Hospital told him his job did not involve crazy treatments for the incurable. Wolff gave his recipe to Bickel, who followed the directions, working in a frigid lab kept cold to prevent the concoction from spoiling.
Eventually, Bickel prepared enough of the stuff for Sheila. He instructed Jones that the girl was to eat nothing else. To his delight, the phenylalanine in Sheila’s bloodstream dropped, and did not bounce back the way it had in Penrose’s experiments fifteen years earlier. The diet even showed signs of improving her brain. Within a few months she began to sit up, then to stand, then to walk with assistance. Her musty odor even disappeared. But when Bickel told his colleagues at the hospital, they scoffed. They were sure Sheila had improved merely thanks to the extra attention she was getting. Bickel decided there was only one way to persuade them: take Sheila off of the diet.
Without telling Jones, Bickel secretly added phenylalanine to the formula. Within a day on the altered diet, Sheila started deteriorating. Soon she stopped smiling, making eye contact, or even walking. Bickel and his coworkers told Jones of their secret maneuver, and put her back on the low-phenylalanine formula. While the transformation was enough proof for Bickel, he didn’t think it would be enough to persuade skeptical colleagues. He got Jones’s permission to bring Sheila into the hospital and feed her phenylalanine again. This time, Bickel captured her decline by filming a silent movie.
In the first scene in the movie, Sheila is on Bickel’s phenylalanine-free diet. She looks healthy and alert. She sits in a high chair, and behind her is draped a curtain covered in fleurs-de-lis. An arm, swathed in a lab-coat sleeve, moves into the frame, dangling a ring of keys. Sheila looks up at the keys. She studies them, and then reaches upward. As she taps the keys, she watches them swing back and forth. Sheila then grasps one of the keys in her own fingers. Now another lab-coat arm moves into the frame, bringing forward a rattle. She makes the difficult choice between keys and rattle calmly. She takes the keys and flings them to the floor.
The next scene was shot after Sheila went back on an ordinary diet for three days. She is a profoundly different child. She sits on the floor, gazing into middle space, her hair a chaotic tuft. When someone shows her keys, she takes several seconds to notice them. She reaches slowly, drooling, but can’t grasp them.
The movie jumps ahead two days. Now Sheila doesn’t even bother to reach for the keys. She just looks at them and cries. The screen turns black again: “Four weeks after resuming her low-phenylalanine diet,” a card reads. In the next scene, Sheila is walking, pushing a chair across the room with stubborn determination. She looks up with an intense gaze—not sad, not happy, perhaps just wondering what she’s been put through.
Bickel’s movie was impressive enough to change the minds of doctors at Great Ormond Street. Wolff, Bickel, and their colleagues got the green light to put more children on the low-phenylalanine diet. In every case, they saw significant improvements. The diet wasn’t a panacea by any means. While the children scored better on intelligence tests, they remained far below average because they had already suffered so much irreversible brain damage. The researchers also saw that the benefits could vanish if parents didn’t sustain the diet every day. Sheila Jones kept getting better, learning to scribble with a crayon and build a tower of bricks. But her mother, a single parent struggling with mental illness, couldn’t keep up Sheila’s demanding diet. Eventually, Mary Jones ended up in an institution, and Sheila had to be put in one as well. Without the diet Bickel and Wolff had invented, Sheila Jones was doomed to live there the rest of her life. She learned to feed and dress herself, but she never learned to speak.
Bickel and Wolff’s breakthrough inspired other scientists and pharmaceutical companies to concoct better formulas. As scientists studied how children on these diets turned out, they found that the earlier they got away from phenylalanine the better off they were in the long run. In the 1950s, however, doctors were still using Følling’s test to detect PKU, which works only after children have built up relatively high levels of phenylpyruvic acid in their urine. To make the diets more effective, they’d need an earlier test.
At the time, scientists knew that PKU was caused by a recessive gene, and they also knew that the gene must be a specific sequence of DNA on a chromosome. But no one knew where it was. Even if they had known, they wouldn’t have been able to sequence it, because the technology required would not become available for many decades. Instead, researchers tried to invent new tests for PKU that could detect lower levels of phenylalanine.
In 1957, a California pediatrician named Willard Centerwall figured out how to diagnose PKU by dabbing a child’s diaper with ferric chloride. His test made it possible for doctors to identify children with the disease when they were still just a few weeks old. Soon afterward, an American medical researcher named Robert Guthrie developed a test that used blood rather than urine. Guthrie’s test was quick, reliable, and cheap. Even better, it could detect PKU in a newborn with just a pinprick’s worth of blood.
These advances were celebrated in the Saturday Evening Post, Time, and the New York Times. Before 1960, only 25 percent of people with PKU lived to the age of thirty, the majority dying young of infections in institutions. But now doctors could detect it and then treat it. Although PKU affected only a few hundred Americans, the press hailed the work of Guthrie and others as an unprecedented victory over heredity.
At the same time, thanks in part to Pearl Buck’s Child Who Never Grew, many parents of retarded children had cast off their shame and were organizing. While there were many causes of retardation, the parents put the spotlight on PKU to inspire more support for care and research. As part of the 1961 National Retarded Children’s Week, President John F. Kennedy welcomed two sisters with PKU, Kammy and Sheila McGrath, to the White House.
Both girls had PKU, but it had affected their lives in fundamentally different ways. Sheila, the older sister, had been diagnosed with PKU when she was a year old. By then she had suffered so much brain damage that at age seven she was now living in an institution. When the McGraths had Kammy two years later, their doctor used Centerwall’s diaper test to diagnose her with PKU at three weeks. The McGraths immediately put her on a diet of special protein powder and low-protein foods. She had avoided Sheila’s toxic exposure, and now, at age five, she was healthy and living at home.
When the McGrath family came to the Cabinet Room of the White House, Kennedy greeted them personally. He led Kammy to a rocking horse and watched her rock on it.
“Attagirl,” the president said. “They are the best behaved children we’ve had in the White House—and that includes those who live here.”
The McGrath family visit is memorialized by an official White House photograph. Kammy and her parents stand by the president, looking at Sheila. She sits on a rocking horse, gazing away. In May the following year, Sheila and Kammy appeared in Life, posing for a photo essay about Guthrie’s test. Kammy, her hair in pigtails, grins over a mountain of protein powder poured onto a table. Sheila, her hair chopped short, is wearing a dark dress and sitting in a rocking chair set back from the table.
The wordless image delivered a clear message: Modern medicine had allowed Kammy to avoid Sheila’s fate. “The sentencing is not mandatory,” the New York Times declared. “Phenylketonuria can be kept in check, if diagnosed early enough, and a child can live a normal life.”
In December 1961, the Kennedy administration panel moved to seek mandatory testing for PKU of all newborns. In 1963, Massachusetts passed a law that required screening for the disease, and other states soon followed. Within ten years, 90 percent of American children were being screened, and Guthrie and other researchers set up PKU testing programs in other countries as well. In later years, other hereditary disorders would be added to newborn screening, giving children as much of a head start as possible. By the 1970s, the first generation of people treated for PKU since birth reached adulthood. They could finish school, hold jobs, have ordinary lives. In 2001, a graduate student named Tracy Beck became the first person with PKU to gain a PhD. She became an astronomer, helping to build the James Webb Space Telescope. For thousands of years, people who inherited the mutations in Beck’s PAH genes would have looked to the sky and not known the word for the lights they saw. Now Beck was helping to extend humanity’s gaze to the farthest edges of the universe.
In 1957, the Vineland Training School decided to test all their students for PKU. One of the few to test positive was Carol Buck.
In one sense, the result was nothing new: Penrose had made the same diagnosis twenty years before, using Følling’s crude test. But this time the school told Pearl Buck. She could finally give Carol’s condition a name, nearly four decades after it had altered her own life.
The name was new to Buck. She studied up on it, and when she traveled to Norway in 1958, she sought out Følling himself. Buck learned as much as she could from the seventy-year-old doctor. Soon afterward, she wrote a letter to her ex-husband, Lossing. She explained to him that they shared an invisible bond, one that neither had known about. After Pearl and Lossing had divorced, he had remarried. He and his second wife had two healthy children. In her letter, Pearl warned Lossing that they may have inherited his dangerous legacy.
“In Carol’s case nothing matters, it is too late,” she wrote. “But I think of your children, who carry the genes in their bodies. It is essential before they marry, that this blood is tested, and the blood of the person they marry.”
In 1960, Willard Centerwall paid Pearl Buck a visit at her home in Pennsylvania. She confided in him that Carol had recently been diagnosed with PKU. From a pocket, Centerwall produced a vial of phenylacetate crystals. He invited Buck to sniff it.
“Immediately she recalled that Carol, as a child, had the same unusual odor,” Centerwall later remembered.
Buck did not write anything about Centerwall’s visit, about smelling an odor that took her back forty years to Nanking, to the bamboo garden where she watched her daughter play. We can’t know what it was like for Buck to suddenly learn that this odor had actually been a signal. It might have told her about her own genetic makeup, about a rare genetic variant that she had inherited from her mother or her father, a variant that Lossing had also acquired from his own ancestry, which they had combined in their child. We don’t know what it was like to discover all this at the very point when children with PKU could at least be treated, to learn that every meal she made for Carol was unwitting poison.
What little we do know comes from her other daughter, Janice. In 1992 Janice recalled that Pearl “had trouble accepting that her family’s genes may have contributed to this disorder.”
In the 1960s, as the first generation of PKU children got to grow up with healthy brains, life went on for Carol and Pearl much as it had for decades. Every December, Pearl wrote a letter to the Vineland Training School, with a list of gifts to be purchased for Carol, who was now in her forties. Crayons and coloring books, beads, glazed fruit, candy, doll blankets, a musical top. The list didn’t change from one Christmas to the next.
In 1972, Pearl paid her last visit to Carol. She had been diagnosed with lung cancer, and her treatments would keep her alive only a few months after the diagnosis. Carol Buck outlived her mother by another twenty years. She, too, was diagnosed with lung cancer. She died at age seventy-two in 1992, and was buried on the grounds of the Vineland Training School, across the street from Emma Wolverton’s grave. Neither Carol nor her mother smoked, raising the possibility that they shared a different mutation that raised their risk of the disease.
PKU is rare, but its story has been told many more times than far more common disorders. It has a powerful moral, but the moral depends on who tells the story.
For some, the story of PKU embodies the triumph of genetics. Mendel’s early followers had been mocked by those who couldn’t believe that experiments on peas could account for why like engenders like. Mendel’s work opened the way to the discovery of genes, and now scientists were finding precise effects of genes on health. Genetics not only explained how PKU arose but allowed doctors to tame it.
In the mid-1980s, a gigantic project took shape that would allow future generations of researchers to quickly find the mutations behind any hereditary disease. Rather than examine the DNA of a single gene, they wanted to sequence every bit of DNA in all forty-six human chromosomes—the entire human genome. “The possession of a genetic map and the DNA sequence of a human being will transform medicine,” promised the Nobel Prize–winning biologist Walter Gilbert.
To show how this transformation would happen, Francis Collins, the director of the National Center for Human Genome Research at the time, offered the PKU story. Scientists found the inherited flaw and then devised a rational treatment for it. “If you simply remove foods with phenylalanine from the child’s diet, he or she will live a normal and healthy life,” Collins declared. Sequencing the entire human genome would make it possible for scientists to pinpoint mutations that caused thousands of other diseases, and potentially open the way to treatments for them as well. “PKU is the example where the paradigm was proven,” Collins said.
To other scientists, however, PKU demonstrated the deep flaws in such gene-centered research. From the earliest days of genetics, researchers recognized that it was a fallacy to talk about a gene being “for” a trait or a disease. Genes don’t have so much power. They exist in an environment, and their effects may be very different in different surroundings. Thomas Hunt Morgan, for example, had observed how a mutation in his flies made them sprout extra legs—but only in cold temperatures.
Once researchers discovered a diet for PKU, it became an even better illustration of the malleability of genes. In 1972, the British biologist Steven Rose declared that PKU demonstrated how pointless it was to talk about something like a “high I.Q.” gene. A variant of the PAH gene could lead to low intelligence test scores if a child was left untreated. Or the same child could score in the normal range if given the right diet.
“Hence the environment has ‘triumphed’ over the genetic deficiency of the individual,” Rose said. “To talk of ‘high I.Q. genes,’ or to try to disentangle the genetic programme from the environment in which it is expressed is both disingenuous and misleading.”
No matter which moral people drew from PKU, their stories had one thing in common: Science had triumphed utterly over the disease. In 1995, the journalist Robert Wright told his own PKU story as a way to attack the idea that our intelligence is fixed by the genes we inherit. In the absence of any treatment, Wright observed, PKU mutations will reliably cause children to have devastating intellectual disabilities. “It turns out,” he cheerfully wrote, “that if you put all infants on a diet low in the amino acid phenylalanine, the disease disappears.”
It should come as no surprise that neither Wright, Rose, nor Collins themselves had PKU, or ever had to care for a child with it. Even with the most sophisticated diets and supplements medicine can offer, PKU never disappears. Starting in the 1950s, children with PKU began to escape the devastation of brain damage, but only if they stuck relentlessly to the dreary regimen of foul-tasting concoctions. Over the years, the PKU foods became tastier, but children growing up on a low-phenylalanine diet still had to watch their friends gorge themselves on pizza and ice cream, sometimes ending up feeling isolated from society.
When the first generation of children with PKU grew up, doctors allowed them as adults to switch to a regular diet. They soon suffered a new round of symptoms as the phenylalanine surged back into their bodies. Now people with PKU are urged to stay on the diet for their entire lives. It’s often a struggle to get the right balance of nutrients each day while avoiding even the slightest trace of phenylalanine. For now, the experience of the disease is a tense negotiation between heredity and the world in which it unfolds.